Community Radiative Transfer Model: Difference between revisions

Revision as of 07:06, 9 June 2023

Revision as of 11:53, 9 June 2023

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The architecture of the CRTM model comprises of the clear-sky model, cloud/aerosol model, and surface model.

* '''Clear-Sky Model:''' ThisThe partclear-sky ofmodel thein CRTM utilizesis opticala depthcritical predictorscomponent tothat performsimulates calculationsthe abouttransmission clearof skyradiant radiativeenergy transferthrough an atmosphere without the presence of clouds. TheThis predictorsmodel arerelies deducedon optical depth predictors, derived from atmospheric profiles of temperature, moisture, and trace gases, to execute its radiative transfer calculations.

To achieve its computations, the clear-sky model employs a number of specific parameters such as:

** '''Temperature and Pressure:''' These parameters play a crucial role in determining the absorption and scattering of radiation in the atmosphere.

** '''Atmospheric Composition:''' This includes the concentrations of various trace gases in the atmosphere, including carbon dioxide, ozone, methane, and others. Each of these trace gases has specific absorption characteristics that impact the transmission of radiation.

** '''Aerosol Concentration:''' While the clear-sky model primarily concerns atmospheres without clouds, it still considers the role of aerosols in scattering and absorbing radiation.

** '''Solar Zenith Angle:''' The angle of the sun above the horizon can significantly affect the pathlength of solar radiation through the atmosphere, thus influencing the total radiation absorbed and scattered.

The clear-sky model reconstructs the atmospheric transmittance using a regression against previously computed line-by-line calculations (using [[LBLRTM]]) for each layer of the atmosphere, integrating these to provide a comprehensive simulation of radiant transmission from the surface to the top of the atmosphere. The primary output of the clear-sky model is the top-of-atmosphere radiance for a given atmospheric and surface state. It's important to note that the clear-sky model is designed to be a high-speed model, aiming to provide a balance between computational efficiency and simulation accuracy.

* '''Cloud/Aerosol Model:''' The cloud/aerosol model simulates the impact of clouds and aerosols on radiative transfer. Clouds and aerosols are treated as non-uniformly distributed layers within the atmospheric column.